3D numerical design of tunnel hood

TL;DR

This study uses a 3D numerical solver to optimize tunnel hood design, reducing pressure wave impact by analyzing shape, section, and length parameters, with findings validated against experimental data.

Contribution

Introduces a parametric 3D numerical approach for tunnel hood design, identifying optimal shapes and dimensions to minimize pressure wave effects.

Findings

Constant section hoods are most efficient.

Optimal hood-to-tunnel section ratio halves pressure wave gradient.

Hood length of 2-8 times train nose length is most effective.

Abstract

This paper relates to the parametric study of tunnel hoods in order to reduce the shape, i.e the temporal gradient, of the pressure wave generated by the entry of a High speed train in tunnel. This is achieved by using an in-house three-dimensional numerical solver which solves the Eulerian equations on a Cartesian and unstructured mesh. The efficiency of the numerical methodology is demonstrated through comparisons with both experimental data and empirical formula. For the tunnel hood design, three parameters, that can influence the wave shape, are considered: the shape, the section and the length of the hood. The numerical results show, (i) that a constant section hood is the most efficient shape when compared to progressive (elliptic or conical) section hoods, (ii) an optimal ratio between hood's section and tunnel section where the temporal gradient of the pressure wave can be reduced by half, (iii) a significant efficiency of the hood's length in the range of 2 to 8 times the length of the train nose. Finally the influence of the train's speed is investigated and results point out that the optimum section is slightly modified by the train's speed.